Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/38—Moulds or cores; Details thereof or accessories therefor characterised by the material or the manufacturing process
  • B29C33/40—Plastics, e.g. foam or rubber
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/56—Coatings, e.g. enameled or galvanised; Releasing, lubricating or separating agents
  • B29C33/60—Releasing, lubricating or separating agents
  • B29C33/62—Releasing, lubricating or separating agents based on polymers or oligomers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C33/00—Moulds or cores; Details thereof or accessories therefor
  • B29C33/38—Moulds or cores; Details thereof or accessories therefor characterised by the material or the manufacturing process
  • B29C33/3842—Manufacturing moulds, e.g. shaping the mould surface by machining
  • B29C33/3857—Manufacturing moulds, e.g. shaping the mould surface by machining by making impressions of one or more parts of models, e.g. shaped articles and including possible subsequent assembly of the parts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2883/00—Use of polymers having silicon, with or without sulfur, nitrogen, oxygen, or carbon only, in the main chain, as mould material

Definitions

• the present invention relates to a process for reproducing works of art and articles manufactured from natural or artificial lapideous material or metal.
• Said washing operation exerts a mechanical action on the polytetrafluoroethylene which is contained in the grease as a thickening agent in the form of a fine powder: being per se insoluble in 1,1,2-trichlorotrifluoroethane, the polytetrafluoroethylene is removed in the form of a suspension.
• the washing also has the function of dissolving the perfluoropolyether: the solubilization is either complete or only partial, depending on the intensity of the treatment with the solvent and on the nature of the material onto which the detaching agent has been applied.
• perfluoropolyether is not completely removed because perfluoropolyethers, as is well known (for example from US-A-4,499,146), exert a protective action on the lapideous materials towards the aggression of atmospheric agents.
• said protective effect attributable to the presence of the perfluoropolyether is not desired in consideration of the successive preservation conditions of the work of art or of the manufactured article (for example in a confined environment), which makes the action of a protective agent useless and suggests the absence of any foreign materials.
• a further drawback may be encountered when the above technique is utilized for lapideous materials having a medium to high porosity, since in such a case it is difficult or even impossible to completely remove the polytetrafluoroethylene: since it is present in the form of a fine white powder, it penetrates into the pores of the material and causes chromatic alterations, which are particularly apparent in natural lapideous materials such as colored sandstones and artificial lapideous materials such as bricks (for example brickwork friezes and bas-reliefs).
• the present invention provides a process for reproducing works of art and articles manufactured from natural or artificial lapideous material or metal, wherein use is made of silicone rubbers to obtain the negative form of the work of art or article and wherein a (preferably thin) layer of fluorinated polymer based on vinylidene fluoride is applied onto the work of art or article prior to the application of the silicone rubber.
• the fluorinated polymer is a vinylidene fluoride homopolymer or copolymer which preferably has the following composition (expressed in % by mols): (a) vinylidene fluoride 50 to 100, preferably 60 to 100; (b) hexafluoropropene 0 to 30; (c) tetrafluoroethylene 0 to 30; (d) chlorotrifluoroethylene 0 to 40.
• the number average molecular weight M n of said polymer generally ranges from about 5.103 to about 5.105, preferably from about 5.104 to about 3.105.
• the vinylidene fluoride terpolymers and copolymers having elastomeric properties composed of:
• non-vulcanized fluoroelastomers utilized as such or in admixture with one another.
• suitable copolymers which are commercially available are Tecnoflon NH® and Viton A® (21% by mols of hexafluoropropene, 79% by mols of vinylidene fluoride), whereas suitable commercially available terpolymers are known as, e.g., Tecnoflon TN® and Viton B®.
• the fluorinated polymer is preferably applied - usually by brushing or spraying - in the form of a solution in an organic solvent, generally at a concentration of from about 1 to about 8% by weight, preferably about 2 to about 5% by weight.
• ketones and/or esters such as methylethylketone, cyclohexanone, acetone, ethyl acetate and butyl acetate, optionally in admixture with a chlorofluorocarbon.
• an azeotropic mixture of acetone (12.5% by weight) and 1,1,2-trichlorotrifluoroethane (87.5% by weight), commercially known as Delifrene AC® and produced by Montefluos may be utilized to particular advantage.
• the fluorinated polymer in the form of an aqueous emulsion, preparable starting from the product directly obtained from the polymerization to which a suitable stabilizer such as Triton X 100® is added and which is optionally diluted with deionized water until reaching a concentration of about 2 to about 6% by weight.
• a suitable stabilizer such as Triton X 100®
• deionized water until reaching a concentration of about 2 to about 6% by weight.
• fluorinated polymer can act effectively as detaching agent: in fact, the polar nature of the polymeric chain based on vinylidene fluoride would be expected to cause a higher adhesiveness and a worse removability as compared to perfluorinated polymers such as polytetrafluoroethylene and perfluoropolyethers.
• the fluorinated polymer layer can detach, at least in part, from the article surface at the moment at which the silicone rubber negative is removed: the removal is then completed, if necessary, by washing with a solvent.
• the complete removal of the fluorinated polymer from the article surface may be verified by recording the infrared spectrum of the powder obtained by scraping off some of said surface: the obtained spectrum should not exhibit the typical absorptions of the C-F and C-H bonds.
• specimen C there was applied (by brushing) a solution (3% by weight in Delifrene AC®)of the fluoroelastomer Tecnoflon NH® ( M n ⁇ 2.105) in an amount of 30 g of polymer per m2 of surface and the solvent was evaporated. Subsequently, as with specimens A and B, the silicone rubber layer was applied.
• example 1 The tests of example 1 were repeated, but using brick specimens having a 40% porosity. Results similar to those of example 1 were obtained and, furthermore, a variation in the original color shade was observed on specimen B.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Laminated Bodies (AREA)
• Adornments (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=11165957

Family Applications (1)

Country Status (2)

Cited By (2)

Family Cites Families (4)

• 1990
  • 1990-05-17 IT IT20351A patent/IT1240653B/it active IP Right Grant
• 1991
  • 1991-05-16 EP EP19910107979 patent/EP0457335A3/en not_active Withdrawn

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